支持 SSL/TLS 的 Objective-C TCP 服务器

Question

我有一个简单的 TCP 服务器/客户端设置。这种连接实际上非常有效。

现在我想为套接字连接实现 SSL/TLS 加密。我使用钥匙串(keychain)访问创建了一个 PKCS12 证书。在我的服务器中，接受回调中有以下代码:

NSString *certificatePath = [[NSBundle mainBundle] pathForResource:@"TCPServerCertificate" ofType:@"p12"];
NSData *certificateData = [NSData dataWithContentsOfFile:certificatePath];

CFArrayRef keyRef;
OSStatus status = SecPKCS12Import((__bridge CFDataRef)certificateData, (__bridge CFDictionaryRef)@{(__bridge NSString *)kSecImportExportPassphrase: @"1234"}, &keyRef);

if (status != noErr) {
    NSLog(@"PKCS12 import error %i", status);
    return;
}

CFDictionaryRef identityDict = CFArrayGetValueAtIndex(keyRef, 0);
SecIdentityRef identityRef = (SecIdentityRef)CFDictionaryGetValue(identityDict, kSecImportItemIdentity);

SecCertificateRef certificate;
status = SecIdentityCopyCertificate(identityRef, &certificate);

if (status != noErr) {
    NSLog(@"sec identity copy failed: %i", status);
    return;
}

NSArray *certificates = [NSArray arrayWithObjects:(__bridge id)identityRef, (__bridge id)certificate, nil];

NSDictionary *settings = @{(NSString *)kCFStreamPropertyShouldCloseNativeSocket:    [NSNumber numberWithBool:YES],
                           (NSString *)kCFStreamSSLValidatesCertificateChain:       [NSNumber numberWithBool:YES],
                           (NSString *)kCFStreamSSLAllowsExpiredCertificates:       [NSNumber numberWithBool:NO],
                           (NSString *)kCFStreamSSLAllowsExpiredRoots:              [NSNumber numberWithBool:NO],
                           (NSString *)kCFStreamSSLAllowsAnyRoot:                   [NSNumber numberWithBool:YES],
                           (NSString *)kCFStreamSSLCertificates:                    certificates,
                           (NSString *)kCFStreamSSLIsServer:                        [NSNumber numberWithBool:YES],
                           (NSString *)kCFStreamSSLLevel:                           (NSString *)kCFStreamSocketSecurityLevelTLSv1};

CFReadStreamSetProperty(readStream, kCFStreamPropertySSLSettings, (CFTypeRef)settings);
CFWriteStreamSetProperty(writeStream, kCFStreamPropertySSLSettings, (CFTypeRef)settings);

然后我创建流的 NSStream 实例并在另一个类中处理它们。

当我运行服务器并连接客户端时，我在我的委托(delegate)中得到了常规的 NSStreamEventOpenCompleted。如果我只是关闭连接，然后尝试写入流或事件，我会收到以下错误:

2013-10-25 13:27:08.584 TCPServer[6435:303] CFNetwork SSLHandshake failed (-9800)
2013-10-25 13:27:08.584 TCPServer[6435:303] NSStreamEventOpenCompleted
2013-10-25 13:27:08.585 TCPServer[6435:303] NSStreamEventErrorOccurred

我想知道我必须在客户端实现什么。另外我想知道为什么在发送数据或从客户端断开连接时会出现握手失败。每当发生此错误时，客户端认为它仍然处于连接状态。

是否有任何好的 TCP SSL/TLS 教程或其他涵盖客户端和服务器端的 Material ？

Answer 1

这段代码有一些问题: 你不能用 kCFStreamPropertySSLSettings 设置 kCFStreamPropertyShouldCloseNativeSocket，你不应该混合服务器和客户端代码。

对于服务器你应该只设置一个证书

CFReadStreamSetProperty(read, kCFStreamPropertyShouldCloseNativeSocket, kCFBooleanTrue);
CFWriteStreamSetProperty(write, kCFStreamPropertyShouldCloseNativeSocket, kCFBooleanTrue);
//kCFStreamPropertySocketSecurityLevel
//Note: If you set this key, you must do so before setting any other SSL options, such as kCFStreamPropertySSLSettings.
CFReadStreamSetProperty(read, kCFStreamPropertySocketSecurityLevel, kCFStreamSocketSecurityLevelNegotiatedSSL);
CFWriteStreamSetProperty(write, kCFStreamPropertySocketSecurityLevel, kCFStreamSocketSecurityLevelNegotiatedSSL);
//Creating server dictionnary

//kCFStreamSSLIsServer
//If the value of this key is kCFBooleanTrue, the kCFStreamSSLCertificates key must contain a valid value

//kCFStreamSSLCertificates
//Security property key whose value is a CFArray of SecCertificateRefs except for the first element in the array, which is a SecIdentityRef.
//For more information, see SSLSetCertificate() in Security/SecureTransport.h.

NSDictionary *settings = @{(id)kCFStreamSSLCertificates:                    certificates,
                           (id)kCFStreamSSLIsServer:                        @YES};


//Apply settings
CFReadStreamSetProperty(read, kCFStreamPropertySSLSettings, (__bridge CFDictionaryRef)(settings));
CFWriteStreamSetProperty(write, kCFStreamPropertySSLSettings, (__bridge CFDictionaryRef)(settings));

对于客户端，如果您想覆盖验证链 (See Apple doc on overriding chain validation)，您应该执行以下操作:

CFReadStreamSetProperty(read, kCFStreamPropertyShouldCloseNativeSocket, kCFBooleanTrue);
CFWriteStreamSetProperty(write, kCFStreamPropertyShouldCloseNativeSocket, kCFBooleanTrue);
//kCFStreamPropertySocketSecurityLevel
//Note: If you set this key, you must do so before setting any other SSL options, such as kCFStreamPropertySSLSettings.

CFReadStreamSetProperty(read, kCFStreamPropertySocketSecurityLevel, kCFStreamSocketSecurityLevelNegotiatedSSL);
CFWriteStreamSetProperty(write, kCFStreamPropertySocketSecurityLevel, kCFStreamSocketSecurityLevelNegotiatedSSL);

//DO NOT USE kCFStreamPropertySSLContext as it overrides the following configuration
//create dictionnary for kCFStreamPropertySSLSettings

//keys for dictionnary we want to change:kCFStreamSSLAllowsExpiredCertificates;kCFStreamSSLAllowsExpiredRoots;kCFStreamSSLAllowsAnyRoot;
//kCFStreamSSLValidatesCertificateChain => no need to worry about the root
//kCFStreamSSLPeerName kCFNull prevents name verification


settings = @{(id)kCFStreamSSLValidatesCertificateChain: @NO,//The delegate will verify this
             (id)kCFStreamSSLPeerName: (id)kCFNull};//prevents name verification if server is not fixed (eg. IP)

//Apply settings
CFReadStreamSetProperty(read, kCFStreamPropertySSLSettings, (__bridge CFDictionaryRef)(settings));
CFWriteStreamSetProperty(write, kCFStreamPropertySSLSettings, (__bridge CFDictionaryRef)(settings));